Test Results: Solar Charging a Panasonic Toughbook

The Panasonic Toughbook range is popular with customers who are nowhere near the grid so solar charging makes particular sense for Toughbook users. We were excited to be able to test drive one to analyze its charging performance.

The best news is that the Toughbook charges directly from our small solar panels, (15 Watt, 20 Volt). This is the first laptop we’ve identified that will take a direct input, with no battery functioning as an intermediary. We saw a power flow of 12.7V x 0.9A = 11.4watts. This is as much as we would expect from this panel when charging a battery at below optimal voltage for the panel (20V). We didn’t get to run it through a full charge cycle from the panel, there has not been a lot of sun in New York lately, but the charge indicator did go up. At that rate, charging the 59 watt hour battery, it would likely take 7-8 hours to fully charge. We also saw that even when it clouded over, the charge continued at a lower rate and picked up again when the sun came back. Most laptop charging circuits do not accept that fluctuation.

The plug for this laptop, and apparently the rest of the Toughbook line, is our “B” laptop adapter, a very common size (5.5mm outside dimension x 2.5mm inside dimension).

We have a battery in development for the Voltaic Generator, so we tested our prototype, a HyperMac 60W and a couple of other 50 watt hour batteries we have floating around. The bottom line is that the Panasonic charge circuitry is really flexible. It charged from everything we connected it to, at either 16V or 19V. Power flow ranged from 29 Watts (13.4V, 2.2A) on the HyperMac to 41.5 on the prototype (13.4V, 3.1A) battery.

Interestingly, it even seemed to get a trickle charge from the 12V output on a couple of batteries, however the power flow was much lower at 2-3 watts, so this may be just some sort of trickle charge circuit.